Pressure sensitive adhesive compositions comprising a curable polymer combined with a tackifier resin are well known in the art.
Pressure sensitive adhesive compositions comprising a hydrolyzable silyl group-containing oxyalkylene polymer among such curable polymers and a tackifier resin can be applied for coating using no organic solvent or using almost no organic solvent and therefore have been proposed as pressure sensitive adhesive compositions exerting no adverse influences on the environment (cf. e.g. Japanese Kokai Publication Sho59-71377). However, the above-mentioned pressure sensitive adhesive compositions are insufficient in adhesive strength and, when a tackifier resin is incorporated in an increased amount so that the adhesive strength may be enhanced, the viscosity of the resulting composition becomes very high and it becomes necessary to use a solvent in an increased amount.
On the other hand, a curable composition comprising a hydrolyzable silyl group-containing high-molecular polymer and a hydrolyzable silyl group-containing low-molecular compound has been proposed (cf. e.g. Japanese Kokai Publication Hei05-59267). This curable composition is known to have a reduced viscosity without any substantial decrease in flexibility and to be effective in avoiding staining of places surrounding the site of application and in preventing the adhesion properties from being adversely affected. However, the use thereof as a pressure sensitive adhesive has not been disclosed.